How Do You Mend a Broken Heart? New Insights into the Links Between Depression and Cardiovascular Disease

There may be no metaphor more pervasive in literature
than the phrase “broken heart.” For centuries, across different languages and
cultures, poets and writers have used the term to describe feelings of great
sadness and longing, usually in response to the loss of a loved one. These
days, the idea of a “broken heart” may be taking on a slightly different
meaning. It’s now understood that depression is strongly associated with
myocardial infarction, or heart attack, as well as other cardiovascular health
issues. Now, researchers from the University of Southern California’s Keck
School of Medicine, have demonstrated a link between depression and atrial
fibrillation, a common arrhythmia or condition of irregular heartbeat.

Heart and mood, mood
and heart

In the early 1990s, a group of Japanese cardiologists first
reported what they called “broken heart” syndrome, or Takotsubo
cardiomyopathy, a condition where individuals, primarily women, experienced
a psychological stress-induced coronary spasm that could lead to heart attack
and, often, death after the loss of a loved one. In the years since,
researchers have learned that Takotsubo cardiomyopathy is not the only
condition to associate feelings of sadness and heart disease. Christopher
Celano, a psychiatrist at Massachusetts General Hospital, says that more and
more studies now demonstrate a strong link between depression and
cardiovascular disease – with depression not only significantly increasing the
risk of heart attack but leading to poorer outcomes after an attack.

“This link is now strong enough that the American Heart
Association recommends screening all patients with cardiovascular disease for
depression,” he says. “We are learning that there is probably a combination of
behavioral and biological mechanisms behind this link. People with depression
are less likely to be active, less likely to eat healthy foods, and less likely
to engage in treatment. That can lead to poorer cardiac outcomes. But we also
know that people with depression frequently have higher levels of inflammation,
which can also result in poor outcomes.”

Inflammation, a common immune response to infection or
injury, is also a common factor in both the development
of depression and cardiovascular
disease. And Viola Vaccarino, an epidemiological researcher who studies the
link between depression and heart disease at Emory University, says that both
disease states are likely due to the same genetic
pathways.

“This isn’t an area that has been explored a lot but it
is possible that the same biological pathways may lead to disease in different
areas—in both mental and physical disease,” she says. “This is something that
we should be exploring more.”

Her work suggests that inflammatory proteins like
Interleukin-6 (IL-6) and C-reactive protein (CRP) are linked to both
depression and heart disease.

“There is a strong possibility that these inflammatory
pathways may predispose someone to depression and, at the same time, also
predispose them to heart disease. This common biological pathway can do
different things in different parts of the body,” she says. “We are also learning
that epigenetics likely plays a role. It’s not just these genes but also the
expression of them. Stress can trigger an inflammatory response, which could
then contribute to heart disease and depression, as well. It’s a complicated
thing to study.”

So complicated, Celano says, that it is difficult to say
whether depression leads to heart disease, or heart disease leads to
depression.

“We know patients with cardiovascular disease have
significantly higher levels of depressive symptoms. If we look at patients with
coronary artery disease, for example, about 40 percent report elevated
depressive symptoms,” he says. “But we also know that people who are depressed
are more likely to develop heart disease sooner than those who are not. It’s a
complex interplay between these factors—and something that requires further
study.”

Depression and atrial
fibrillation

Researchers from the Keck School of Medicine at the
University of Southern California added a new piece to this complicated puzzle
at the American Heart Association’s Epidemiology and Prevention meeting this
past March. Praveen Garg, an assistant professor of clinical medicine, reported
new results linking
depression with atrial fibrillation (a-fib), a common heart rhythm disorder.
Garg and associates followed more than 6,600 people with no known history of
heart disease over time. The researchers found a strong association: People who
scored highest on a clinical screening for depression or were prescribed
anti-depressant medication, had more than a 30 percent higher risk for
developing atrial fibrillation than those with no indicators of depression.

“There is some literature out there to suggest that
mental health may be related to atrial fibrillation. In particular, things like
anxiety, stress, and tension. That suggests there could also be a link to
depression,” he says. “But this is the first time anyone has formally tested
this association and found a link.”

What might be behind such a link? Garg says that
increased levels of inflammation may be one factor—clinical evidence suggests that
a-fib is an inflammatory disease. But this study is preliminary and more
work needs to be done to thoroughly understand the link.

“We need to confirm that this relationship exists in
other populations, studies where we formally test for depression rather than
rely on questionnaires and prescriptions,” he says. “Once we do that, we can
start to get a better idea of what mechanisms might be behind such a
relationship.”

What’s good for
the heart Is good for the brain

Garg says that this study adds another piece to the
puzzle regarding heart disease and mental health and will help clinicians what
risk factors are related to poor heart health.

“The take-home message is that atrial fibrillation is a
growing problem. It’s a disease of aging and the United States population is
aging,” he says. “Clinicians need to recognize that depression, if present, may
also place these individuals at risk for the development of this heart rhythm
disorder. So doing an in-depth assessment of depressive symptoms in cardiac
patients is important.”

Vaccarino hopes that more laboratories will do research
to help understand the common biological pathways, like inflammation, and how
they may result in different forms of disease. But, in the meantime, she agrees
with Garg that both clinicians and patients should be aware of this connection
between heart health and depression and do what they can to maintain good
health.

“The genetics are important and can help us
understand our baseline risk for these different diseases and perhaps point us
in the direction of new treatments,” she says. “But we don’t have to wait for
those studies. You can act on the things that can be modified like diet,
physical activity, and smoking. We know all of these things impact heart
disease and depression, and also help with inflammation. They can help reduce
your risk.”